1. Field of the Invention
This invention relates to an image forming which forms an image by use of electron beam, and more particularly to an image forming device by use of an electron beam generating device provided with a plural number of electron beam generating sections.
2. Related Background Art
In recent years, electron beam generating devices which use of a cold cathode have been developed, as disclosed in Japanese Patent Publication No. 30274/1979, Japanese Laid-Open Patent Publication No. 111272/1979 (corresponding to U.S. Pat. No. 4,259,678), Japanese Laid-open Patent Publication No. 15529/1981 (corresponding to U.S. Pat. No. 4,303,930), Japanese Laid-Open Patent Publication No. 38528/1982, etc.
The cold cathode in the above electron beam generating device, in contrast to the hot cathode most generally employed in electron beam generating devices in which a great restriction is imposed in the degree to which it is practiced to decreasing the electron-releasing surface area, due to the problem of durability, has the advantage of substantially avoiding such restriction. Also, hot electrodes cannot easily be arranged in a plural number with uniform characteristics with high positional precision, while cold electrodes can be advantageously arranged in a plural number with uniform characteristics and high positional precision by forming them using such a production process such as photolithography or electron beam lithography. Therefore, such or analogous technique make it possible to obtain an electron beam generating device provided with a large number of electron beam generating sections, and application of this technique in various image forming devices, typically display devices, has been hoped for.
However, when increase in capacity of the image forming device is attempted by an electron beam generating device having a plural number of electron beam generating sections arranged two-dimensionally as described above, the following problems are involved. First, when an image is to be formed by deflection scanning of the electron beams emitted from the above electron beam generating device, there is the problem of distortion of image as the deflection angle becomes greater. This distortion can with difficultly be corrected by an electron optical system which corrects the distortion of a point electron source of the prior art, since the group of electron beams has a two-dimensional size.
Also, in the prior art, the cold cathode type of solid electron beam generating device to be used for this kind of image forming device (hereinafter referred to as a cold cathode type member) has been considered for application to display devices, recording devices, etc., for such reasons as low actuation temperature, high electron generation density (current density), etc., and various proposals have been made.
FIG. 14 shows a schematic illustration of a cold cathode member of the prior art. The cold cathode member shown in FIG. 14 is disclosed in Japanese Laid-Open Patent Publication No. 14429/1981, and generates electron beams by supplying reverse voltage to the semi-conductor, which has a p-n junction.
In FIG. 14, 101 is a p-type semiconductor of silicon, 102 is an n-type semiconductor of silicon, 103 is electrodes for applying reverse bias to the p-n junction semiconductor, 104 is an insulator, 105 is a window for generating electrons, 106 is an accelerating electrode for acceleration of electrons generated, 107 is a detector for measuring the amount of electron beam, 108 is an ammeter for displaying the magnitude of the electron beam detected by 107 as a current density, 109 is a power source for applying voltage to the p-n junction semiconductor, and 100 is a power source for applying voltage to the accelerating electrode 106. In the above construction, when a predetermined reverse voltage is applied from the power source 109 to the p-n junction semiconductor, avalanche breakdown occurs in the semiconductor. As a result, electrons in the vicinity of the p-n junction semiconductor acquire great kinetic energy, and the electrons are released from the window 105. The released electrons are further accelerated by the accelerating electrodes, 106 to which is applied a constant voltage of 5 to 150 V, to become electron beams.
In the prior art, the cold cathode members of these image forming devices become elevated in temperature during actuation, whereby the discharge amount of electron beam varies and therefore the driving voltage on the cold cathode member is required to be successively changed for compensation for the variation, thus involving the drawback that it can be actuated continuously only with difficulty. For example, when this kind of a cold cathode member is used at the cathode portion of CRT, the temperature of the cathode itself becomes higher to vary the amount of electron beam or beams generated, whereby there has been the drawback that the appropriate luminance cannot be obtained. In order to obtain again the appropriate luminance, the cathode is required to be cooled and therefore continuous actuation could only with difficulty be done.